Monitoring Stack with Cephadm

Ceph Dashboard uses Prometheus, Grafana, and related tools to store and visualize detailed metrics on cluster utilization and performance. Ceph users have three options:

  1. Have cephadm deploy and configure these services. This is the default when bootstrapping a new cluster unless the --skip-monitoring-stack option is used.

  2. Deploy and configure these services manually. This is recommended for users with existing prometheus services in their environment (and in cases where Ceph is running in Kubernetes with Rook).

  3. Skip the monitoring stack completely. Some Ceph dashboard graphs will not be available.

The monitoring stack consists of Prometheus, Prometheus exporters (Prometheus Module, Node exporter), Prometheus Alert Manager and Grafana.

Note

Prometheus’ security model presumes that untrusted users have access to the Prometheus HTTP endpoint and logs. Untrusted users have access to all the (meta)data Prometheus collects that is contained in the database, plus a variety of operational and debugging information.

However, Prometheus’ HTTP API is limited to read-only operations. Configurations can not be changed using the API and secrets are not exposed. Moreover, Prometheus has some built-in measures to mitigate the impact of denial of service attacks.

Please see Prometheus’ Security model <https://prometheus.io/docs/operating/security/> for more detailed information.

By default, bootstrap will deploy a basic monitoring stack. If you did not do this (by passing --skip-monitoring-stack, or if you converted an existing cluster to cephadm management, you can set up monitoring by following the steps below.

  1. Enable the prometheus module in the ceph-mgr daemon. This exposes the internal Ceph metrics so that prometheus can scrape them.:

    ceph mgr module enable prometheus
    
  2. Deploy a node-exporter service on every node of the cluster. The node-exporter provides host-level metrics like CPU and memory utilization.:

    ceph orch apply node-exporter '*'
    
  3. Deploy alertmanager:

    ceph orch apply alertmanager 1
    
  4. Deploy prometheus. A single prometheus instance is sufficient, but for HA you may want to deploy two.:

    ceph orch apply prometheus 1    # or 2
    
  5. Deploy grafana:

    ceph orch apply grafana 1
    

Cephadm handles the prometheus, grafana, and alertmanager configurations automatically.

It may take a minute or two for services to be deployed. Once completed, you should see something like this from ceph orch ls:

$ ceph orch ls
NAME           RUNNING  REFRESHED  IMAGE NAME                                      IMAGE ID        SPEC
alertmanager       1/1  6s ago     docker.io/prom/alertmanager:latest              0881eb8f169f  present
crash              2/2  6s ago     docker.io/ceph/daemon-base:latest-master-devel  mix           present
grafana            1/1  0s ago     docker.io/pcuzner/ceph-grafana-el8:latest       f77afcf0bcf6   absent
node-exporter      2/2  6s ago     docker.io/prom/node-exporter:latest             e5a616e4b9cf  present
prometheus         1/1  6s ago     docker.io/prom/prometheus:latest                e935122ab143  present

Using custom images

It is possible to install or upgrade monitoring components based on other images. To do so, the name of the image to be used needs to be stored in the configuration first. The following configuration options are available.

  • container_image_prometheus

  • container_image_grafana

  • container_image_alertmanager

  • container_image_node_exporter

Custom images can be set with the ceph config command:

ceph config set mgr mgr/cephadm/<option_name> <value>

For example:

ceph config set mgr mgr/cephadm/container_image_prometheus prom/prometheus:v1.4.1

Note

By setting a custom image, the default value will be overridden (but not overwritten). The default value changes when updates become available. By setting a custom image, you will not be able to update the component you have set the custom image for automatically. You will need to manually update the configuration (image name and tag) to be able to install updates.

If you choose to go with the recommendations instead, you can reset the custom image you have set before. After that, the default value will be used again. Use ceph config rm to reset the configuration option:

ceph config rm mgr mgr/cephadm/<option_name>

For example:

ceph config rm mgr mgr/cephadm/container_image_prometheus

Disabling monitoring

If you have deployed monitoring and would like to remove it, you can do so with:

ceph orch rm grafana
ceph orch rm prometheus --force   # this will delete metrics data collected so far
ceph orch rm node-exporter
ceph orch rm alertmanager
ceph mgr module disable prometheus

Deploying monitoring manually

If you have an existing prometheus monitoring infrastructure, or would like to manage it yourself, you need to configure it to integrate with your Ceph cluster.

  • Enable the prometheus module in the ceph-mgr daemon:

    ceph mgr module enable prometheus
    

    By default, ceph-mgr presents prometheus metrics on port 9283 on each host running a ceph-mgr daemon. Configure prometheus to scrape these.

  • To enable the dashboard’s prometheus-based alerting, see Enabling Prometheus Alerting.

  • To enable dashboard integration with Grafana, see Enabling the Embedding of Grafana Dashboards.

Enabling RBD-Image monitoring

Due to performance reasons, monitoring of RBD images is disabled by default. For more information please see RBD IO statistics. If disabled, the overview and details dashboards will stay empty in Grafana and the metrics will not be visible in Prometheus.